Device for picking up one piece of cloth from a stack of cloth pieces

ABSTRACT

This invention relates to a device for picking up one piece of cloth (1) from a stack (2) of cloth pieces. In order that a piece of cloth could be picked up reliably irrespective of the kind of the cloth to be picked up, the device comprises a sticker member (3) for gripping the piece of cloth (1) to be picked up at the edge region thereof and for raising the edge of the piece of cloth to be picked up by turning the sticker member, an elongated support structure (8) comprising an elongated strip (4) of magnetizable metal and separating blades (6, 7) positioned on both sides of said strip, the support structure being arranged to be inserted under the piece of cloth (1) to be picked up from the side of the raised edge thereof, an elongated magnetic bar (5) positioned opposite to the magnetizable strip for locking the piece of cloth (1) to be picked up between the magnetic bar (5) and the magnetizable strip (4); and finally the separating blades ( 6, 7) are displaced in opposite sideward directions with respect to the magnetizable strip (4) for wholly separating the piece of cloth (1) to be picked up from the other pieces of cloth.

This invention relates to a device for picking up one piece of clothfrom a stack of cloth pieces, comprising means for gripping and raisingthe edge of a piece of cloth to be picked up; and means intended to beinserted under the piece of cloth to be picked up from the side of theraised edge thereof for separating and supporting the piece of cloth.

In clothing industry, it is customary to cut cloths used for themanufacture of garments by means of automatic cutting means which cutseveral cloths at a time. Such cut pieces of cloth form stacks in whichthere are several layers of cloth. In practice, it has proved difficultto automatically pick up one piece of cloth from such a stack andvarious methods and devices have been suggested for the purpose. Suchdevices include suction-type and sticker-type devices. In suction-typedevices a major problem has been that suction applied to the stack ofcloth pieces tends to take with it more than one piece of cloth. Insticker-type devices, on the other hand, the performance of the stickingmeans deteriorates in the long run, so that such devices are unreliablein long-term use especially when transferring pieces of cloth. Anexample of a more advanced technique is an arrangement in which an airjet is applied to the topmost piece of cloth in a stack from the midarea of the cloth towards its edge, so that the piece of cloth is causedto vibrate, being thus separated from the other cloth pieces. While theedge of the topmost layer "flutters", one arm of an accurately directedgripping jaw can be inserted under the piece of cloth so that the pieceof cloth will be positioned between the elongated gripping jaws. Similaror closely related techniques and devices, in which particularly thestructure of the means raising the edge of the piece of cloth to bepicked up varies, are disclosed e.g. in German Offenlegungsschrifts 3419 056 and 3 634 699 and U.S. Pat. No. 4 231 563. These techniques,however, are rather sensitive to the change of the kind of cloth andrequire in any case accurate adjustment for each kind of cloth to beoperative.

The object of the present invention is to provide a device for pickingup one piece of cloth from a stack of cloth pieces, which device is mostreliable and is operative irrespective of the kind of the piece of clothto be picked up.

This object is achieved by means of a device according to the inventionwhich is characterized in that the separating and supporting meanscomprising an elongated strip of magnetizable metal, and separatingblades positioned on both sides of said strip, the support means beingarranged to be inserted under the piece of cloth to be picked up fromthe side of the raised edge thereof; an elongated magnetic barpositioned opposite to the magnetizable strip for locking the piece ofcloth to be picked up between the magnetic bar and the magnetizablestrip; and means for displacing the separating blades in oppositesideward directions with respect to the magnetizable strip for whollyseparating the piece of cloth to be picked up from the other pieces ofcloth in the stack. Further, it is preferable that said means forgripping and raising the edge of the piece of cloth to be picked upcomprise a sticker member having a surface of an adhesive material forgripping the piece of cloth to be picked up at the edge region thereof;and means for turning the sticker member for raising the edge of thepiece of cloth to be picked up apart from the stack.

In the following the device according to the invention will be describedin more detail with reference to the attached drawing, in which thefigure shows by way of example one specific embodiment of the deviceaccording to the invention.

The figure exemplifies a device for picking up one piece of cloth 1 froma stack 2 of cloth pieces. In the figure, the stack 2 is placed on avertically adjustable table 10 and it is pressed by holders 9. A stickermember 3 is provided above the stack 2 so as to be pressed with asubstantially constant force against the stack 2. The sticker member 3and an elongated magnetic bar 5 attached thereto are suspended from acarriage 12 supported displaceably on a support beam 11.

A support means 8 to be inserted under the piece of cloth 1 to be pickedup comprises a strip of magnetizable metal, such as a steel strip 4, andelongated separating blades 6 and 7 usually positioned on the sides ofthe metal strip 4 for supporting it. The metal strip 4 is suspended froma carriage 13 supported on the support beam 11 so as to be displaceabletherealong, in synchronization with the carriage 12, if required. Theseparating blades 6 and 7, in turn, are supported by a table 16 arrangedon support bars 14 and 15. The separating blades 6 and 7 aredisplaceable on the support table 16 substantially perpendicularly insideward directions with respect to the metal strip 4. The support table16 is also displaceable in the longitudinal direction of the supportbars 14 and 15.

The device shown in the figure operates in the following way. Initially,the support means 8 is in its retracted position, whereby both thesupport table 16 and the support carriage 13 have been displaced as farbackwards as is necessary for getting the support means 8 away from thearea of the stack 2 of cloth pieces, in the figure to the right. At thefirst picking stage, the sticker member 3 is pressed with asubstantially constant force against the edge region of the topmostpiece of cloth 1 in the stack 2. This requires, of course, that thetable 10 and the carriage 12 supporting the sticker member 3 have beenproperly aligned with each other in advance. After the sticker member 3has been pressed against the edge region of the piece of cloth 1 to bepicked up, the sticker member 3 is turned with suitable means (notshown) and the table 10 is lowered so that the edge of the cloth to bepicked up is separated from the other cloth pieces. Thereafter, thesupport means 8 formed by the metal strip 4 and the separating blades 6and 7 is displaced forwards so as to be inserted under the piece ofcloth 1 to be picked up. The forward displacement of the support means 8naturally requires that the movement of the table 16 supporting theseparating blades 6 and 7 and that of the carriage 13 supporting themetal strip 4 are synchronized with each other. After the support means8 has been inserted under the piece of cloth 1 to be picked up, amagnetizing current is connected to the elongated magnetic bar 5 formingan extension of the sticker member 3 so that the piece of cloth 1 islocked between the metal strip 4 and the magnetic bar 5, and the table10 is again lifted up. Thereafter, the separating blades 6 and 7 aredisplaced in opposite sideward directions with respect to the metalstrip 4 for wholly separating the piece of cloth 1 from the other clothpieces. In this situation, the piece of cloth 1 remains between themagnetic bar 5 and the metal strip 4 attracted by said magnetic bar. Inorder that the piece of cloth 1 could be transferred away, the holders 9are released so that the stack 2 is pressed by the separating blades 6and 7 only. After the piece of cloth to be picked up has beentransferred, the holders 9 are fastened in place again. At a subsequentstage, the table supporting the stack 2 of pieces of cloth is lowereddown, whereby by displacing the carriages 12 and 13 simultaneously alongthe support beam 11 the piece of cloth 1 can be transferred without anyhindrance to the following process step. The piece of cloth 1 can beremoved from the picking device according to the invention e.g. bylowering the piece of cloth 1 on a suitable surface, whereafter it isgripped with suitable gripping means, the magnetic bar 5 is demagnetizedand the metal strip 4 is withdrawn from under the piece of cloth.Thereafter the carriage 12 with the magnetic bar 5 and sticker member 3thereof can be displaced to the initial position for picking up anotherpiece of cloth.

Due the operating principle of the technique according to the invention,one and only one piece of cloth can be picked up from a stack extremelyreliably. However, it is preferable to provide the sticker member 3 witha suitable sensor measuring e.g. the thickness of the cloth piece forensuring that one piece of cloth only sticks to the sticker member. Ifthis is not the case, attempts can be made to separate the pieces ofcloth from each other e.g. by means of a suitable air jet after the edgeregion of the cloth pieces has been turned upwards by means of thesticker member. The surface of the sticker member 3 may be made ofvarious adhesive materials known per se so that it sticks well to thecloth but nevertheless is easy to separate therefrom. In use, however,filaments of cloths picked up always adhere to such an adhesive surface,wherefore the surface has to be renewed every now and then. This may becarried out by heating the adhesive material so that the filamentsadhering thereto sink into the adhesive material and a new surface withgood sticking properties is formed. In this way the sticker member canbe renewed several times before it has to be replaced with a new one.Since the function of the sticker member in the device according to theinvention is not to raise the whole cloth piece to be picked up but onlythe edge thereof, the sticker member does not have to fulfill standardsby far as high as in picking devices in which the sticker member shouldeffect the whole lifting process.

The device according to the invention has been described above by meansof one specific embodiment and it is to be understood that it can bemodified in various ways without deviating from the scope of protectiondefined in the attached claims.

What is claimed is:
 1. A device for picking up a piece of cloth (1) froma stack (2) of cloth pieces, comprisingmeans (3) for gripping andraising the edge of the piece of cloth (1) to be picked up; and meansintended to be inserted under the piece of cloth (1) to be picked upfrom the side of the raised edge thereof for separating and supportingthe piece of cloth (1), characterized in that the separating andsupporting means comprise elongated support means (8) comprising anelongated strip (4) of magnetizable metal and separating blades (6, 7)positioned on both sides of said strip, said separating blades beingarranged to be substantially displaceable perpendicularly with respectto a longitudinal axis of the magnetizable strip (4), the support meansbeing arranged to be inserted under the piece of cloth (1) to be pickedup from the side of the raised edge thereof; an elongated magnetic bar(5) positioned opposite to the magnetizable strip for locking the pieceof cloth (1) to be picked up between the magnetic bar (5) and themagnetizable strip (4); and means for displacing the separating blades(6, 7) in sideward directions with respect to the magnetizable strip (4)for wholly separating the piece of cloth (1) to be picked up from theother pieces of cloth in the stack (2).
 2. A device according to claim1, characterized in that the magnetizable strip (4) is arranged to besupported by the separating blades (6, 7) prior to the magnetization ofthe magnetic bar (5).
 3. A device according to claim 1, characterized inthat said means (3) for gripping and raising the edge of the piece ofcloth to be picked up comprisea sticker member having a surface of anadhesive material for gripping the piece of cloth to be picked up at theedge region thereof; and means for turning the sticker member forraising the edge of the piece of cloth (1) to be picked up apart fromthe stack (2).
 4. A device according to claim 4, characterized in thatthe sticker member (3) having a surface of an adhesive materialcomprises means for heating the adhesive material for the renewalthereof.